Cod 4 Xbox, no maps/game modes?

I have cod 4 bought from the xbox live market place. My brother joined a hacked server and since then we appear to be set a level 0. We cannot select any game mode, all are grey (not white) and say must reach level 1 before you can access them. I have no idea how to fix this and have briefly googled it but found no solutions. Any help would be greatly appreciated,

CheersCod 4 Xbox, no maps/game modes?
Your account has been bannedCod 4 Xbox, no maps/game modes?
Sorry, you have been banned, that's what happens to kiddos like you who want hacks.

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